The present invention relates to a dispenser of volatile liquids, and more particularly to a device for evaporating liquid moving up a wick.
Wick-based liquid volatile dispensing systems are known in the art for dispersing vaporized particles of any number of liquids into the air. Such systems are often used in the home with liquids varying from insect repellents to air fresheners. One end of a wick can be submerged in the liquid to be dispersed. The submerged portion of the wick absorbs the liquid, some of which diffuses by capillary or wicking action into the exposed, unsubmerged portion of the wick. The exposed portion of the wick is locally heated, often by means of a ring-shaped heater which fits about the exposed tip of the wick. This causes the liquid which has diffused into the exposed portion of the wick to evaporate into the surrounding air. Continual application of heat to the exposed portion of the wick results in an evaporation process that continues until the liquid is consumed.
The primary difficulty associated with conventional heated wick liquid dispensers is controlling the dispersion of the volatile materials, particularly the rate and distance of dispersion of the volatile materials.
The evaporation rate of the volatile materials must be rapid enough to begin dispersing volatiles shortly after it is activated, and yet provide sustained release over a useful life. The dispersion rate can also vary over time. Upon first activating the dispenser (after the heater reaches operating temperature), the release rate is typically greater than after several hours of use. Therefore, it is difficult to select components and the appropriate amount of liquid to use for a given application.
The evaporated volatile materials usually must emanate through a relatively large air space, for example, one or more rooms of a house. Extremely localized dispersion limits the effect of the volatile to the immediate area around the dispenser. Sometimes, a portion of the evaporated materials becomes trapped inside the housing of the dispenser. This can cause it to condense within the housing, and in severe cases, can result in liquid dripping out of the bottom of the dispenser. Loss of liquid through evaporation when the heater is deactivated is also common. Sometimes condensation of the warm air stream can leave deposits of volatized active materials at the exterior of the housing, particularly at or around the outlet opening. This can be unsightly and leave the deposited material susceptible to contact by the user.
Another problem with electric volatile dispensers pertains to providing a clear indication to the consumer that the device is operating. This includes provides immediate feedback of activation to the consumer even when there is some delay in dispersion of the volatile, as when the heater is warming up to operating temperature. It also helps the consumer know that the device, since activated, may be warm. It can also indicate to the consumer that the device should be unplugged if the liquid has been exhausted.
A light is commonly used to provide an in-use indication. The lamp is powered when the dispenser is plugged into an electrical outlet and thus illuminates only when the dispenser is powered. Sometimes, the dispenser housing has a small translucent window or is partially, or totally, constructed of translucent material so that the light is visible from outside the housing. The opening or translucent area is usually at the top of the dispenser, which is at the height of the electrical outlet, so it can be viewed readily from a person standing nearby. Having a light opening in the housing is problematic because liquids and small objects, fingers for example, can enter there. A separate translucent window adds to assembly and translucent components add to the cost of the product. Another concern relevant to evaporative dispensers is that the lamp is often exposed to the heat source, which makes it apt to burn out more rapidly.
Accordingly, there is a need for a liquid volatile dispenser that better addresses the aforesaid problems.